The LEDs voltage tolerances are often more than 0.1V either way, so what voltage do you aim at...?
I am aware that you may have been asking a rhetorical question, but I wasn't sure.
QuoteThis is why controlling LEDs with resistors is a bad idea,It is not a bad idea it is done all the time in a lot of professional applications and is quite satisfactory technique. It is not the technique to get the absolute exact control over the current but often this is not necessary.
This is why controlling LEDs with resistors is a bad idea,
How does using an LED Driver IC differ from powering the LEDs through a PWM enabled pin